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Insecure encryption algorithm - DSA

Need​

Implementation of a secure encryption algorithm

Context​

  • Usage of Ruby for building dynamic and object-oriented applications
  • Usage of OpenSSL for secure communication and encryption

Description​

Non compliant code​

require 'openssl'

private_key = OpenSSL::PKey::DSA.new 1024
cipher =  OpenSSL::Cipher.new 'DES-EDE3-CBC'

public_key = private_key.public_key
data = "Sensitive Data"

encrypted_string = private_key.public_encrypt(data, cipher)

The above Ruby code is using the DSA (Digital Signature Algorithm) for encryption which is considered insecure. The DSA algorithm is not recommended for use in new systems because it is more vulnerable to attacks than other, more modern algorithms.

The code starts by requiring the 'openssl' library which provides SSL and TLS protocols for secure communications. It then generates a new DSA private key of 1024 bits. The cipher used is 'DES-EDE3-CBC', which is also considered insecure due to its small key size and susceptibility to certain attacks.

The public key is then extracted from the private key and a string "Sensitive Data" is encrypted using this public key and the DES-EDE3-CBC cipher.

The vulnerability lies in the use of the DSA algorithm and the DES-EDE3-CBC cipher for encryption. Both of these are outdated and have known vulnerabilities, making the encrypted data susceptible to decryption by an attacker.

Steps​

  • Replace the insecure encryption algorithm (DSA) with a secure encryption algorithm.
  • Use a strong encryption algorithm such as AES (Advanced Encryption Standard) instead.
  • Update the code to use the recommended encryption algorithm provided by the framework or library being used.
  • Ensure that the encryption algorithm used is considered secure and not vulnerable to known attacks.
  • Consider using a higher key size for stronger encryption.
  • Follow best practices and guidelines for encryption implementation.
  • Regularly update the encryption algorithm and libraries used in the application to stay protected against new vulnerabilities.

Compliant code​

require 'openssl'

private_key = OpenSSL::PKey::RSA.new 2048
cipher =  OpenSSL::Cipher.new 'AES-128-CBC'

public_key = private_key.public_key
data = "Sensitive Data"

encrypted_string = public_key.public_encrypt(data)

The original code was using the DSA encryption algorithm, which is considered insecure. The updated code now uses the RSA encryption algorithm, which is more secure.

The key size has also been increased from 1024 to 2048 bits. This provides a higher level of security as it makes it more difficult for an attacker to break the encryption.

The cipher has been changed from 'DES-EDE3-CBC' to 'AES-128-CBC'. AES (Advanced Encryption Standard) is a more secure symmetric encryption algorithm compared to DES (Data Encryption Standard).

The public_encrypt method no longer takes a cipher as a parameter. This is because the RSA encryption algorithm does not require a separate symmetric encryption algorithm to be specified.

By making these changes, the encryption of the data in the application is now more secure and less vulnerable to attacks. It's important to regularly review and update the encryption methods used in the application to ensure they remain secure as new vulnerabilities are discovered.

References​

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